In abrasive applications such as electric submersible pumps a sleeve is used to rotate with the shaft of a multistage pump inside a bushing. To handle the abrasive particles the sleeve and the bushing are frequently made of tungsten carbide. In the past the way the sleeve was attached to the shaft was to put a keyway in the sleeve and in the shaft and line up the keyways and insert a key in the keyway that spanned the shaft and the sleeve. In operation under torque loading, the shaft would flex so that one part of the sleeve was rotated to a small degree with respect to another part generally at the opposite end of the sleeve. The keyway by its nature required a portion of the wall removed and became a location of stress concentration. Add to that the brittle nature of carbide and the result was that there were cracks and failures in the sleeve.
One solution for this problem was to use a keyless connection between the shaft and the sleeve as illustrated in U.S. Pat. No. 7,182,584 and shown in FIGS. 4 and 5. Here the sleeve 98 came with depressions 108 and the retainer was fixed to the shaft in an undisclosed manner and had protrusions 106 that registered with depressions 108 in an effort to ensure that the shaft rotated with the sleeve 98. While somewhat schematic, FIG. 2 shows journal bearings 42 that seem to have the retaining rings held fast by snap rings that are not identified with a number.
Other art relating generally to shafts, sleeves and the application of springs to such designs are U.S. Pat. Nos. 6,725,937 and 6,956,310 and U.S. Publications 2005/0109515 and 2010/0008796.
The present invention seeks to mount the sleeve to the shaft without a keyway and form the engagement for torque transfer in a manner that allows slippage from over-torque with an ability to recover and obtain another grip. The torque transfer uses preferably rounded extending shapes from one of the retaining ring or the sleeve while making most of the mating surfaces flat and conducive to relative rotation when an over-torque situation arises. The opposed retainer rings are made of a mild steel material and keyed against rotation to the shaft but are also preferably biased axially by spring force that promotes contact but allows recovery from relative rotation after an over-torque occurrence passes. These and other aspects of the present invention will be more readily understood by those skilled in the art from a review of the detailed description of the preferred embodiment and the associated drawings while understanding that the full scope of the invention is to be determined by the appended claims.